Conventional coal and oil combustion is still the main energy source for electricity generation and for powering cars and modern jets. However, these technologies cause air pollution and global warming.
In conventional jet engines, air is compressed and slowed down by means of compressors and then mixed with fuel before entering a combustion chamber. The hot products of the reaction from combustion then drive turbines, which have a common axis with the compressors. The hot products converge through a nozzle and accelerate out of the nozzle, thereby producing forward moving force. The net thrust of a jet engine is a result of pressure and momentum changes within the engine. Some of these changes produce forward forces, yet some produce rearward or backward forces. The major rearward forces are due to the energy used to drive the turbines. Therefore, a fraction of the energy is left for jet engine thrust.
Pulsed jet engines, pulse detonation engines, and other similar types of engines have the simplicity and efficiency of combustion engines, at least in principle. Such engines have drawn attention over the last 70 years. Generally, in conventional pulsed engines and detonation engines, one pipe extends from the combustion chamber, which causes a recoiled shock wave.
Pulsed jet engines are used today in drone aircraft, flying control line mode aircraft, radio-controlled aircraft, fog generators, industrial drying and home heating equipment. The pulse detonation engine (PDE) marks a new approach towards non-continuous jet engines and promises higher fuel efficiency compared to turbofan jet engines, at least at very high speeds. Currently, Pratt & Whitney and General Electric have active pulse detonation engine research programs. Most pulse detonation engine research programs use pulsed jet engines for testing ideas early in the design phase. Boeing has a proprietary pulse jet engine technology called Pulse Ejector Thrust Augmenter (PETA). These engines are relatively difficult to integrate into commercial manned aircraft designs because of noise and vibration, although they excel on smaller-scale unmanned vehicles. Although pulse detonation engines have been considered for propulsion for over 70 years, practical pulse detonation engines have yet not been put into high volume production.
Generally, turbine engines have been used to propel vehicles (e.g., jets) and to generate industrial electrical power and central power. Typically, a turbine engine includes a compressor, a combustor, and a turbine in a sequential arrangement. Influent air is compressed to a high pressure in the compressor and is fed at a high speed and pressure into the combustor, where the air is mixed with a fuel and is combusted to produce a hot, pressurized stream of gas that is passed into the turbine section, where the gas expands and drives a turbine. The turbine converts the energy (e.g., enthalpy) of the gas into mechanical work that drives the compressor and optionally other devices coupled to the gas turbine.
FIG. 1A shows a conventional turbine engine 100 which is typically used in airplanes and power generation. The gas turbine engine 100 of FIG. 1A includes a compressor section 114 (which may have multiple stages) for increasing the pressure and temperature of influent air (e.g., at air intake 112); a combustion section or chamber 116 that may have multiple combustion chambers located around the perimeter of the engine, in which fuel is ignited to further increase the temperature and pressure of the influent air; and a turbine section 118 in which the hot, pressurized air or exhaust 120 is delivered to drive the rotors of the turbine and generate mechanical energy to spin the central axle of the turbine and generate power and/or thrust.
Although recent technology advancements have enabled the use of smaller, lighter gas turbines that are more efficient and less polluting than other engine types (e.g., combustion engines), the efficiency of gas turbines can be improved. For example, conventional natural gas-fired turbine generators convert only between 25 and 35 percent of the natural gas heating value to useable electricity. In addition, conventional engines carry a heavy load of fuel and oxidizers. Furthermore, conventional engines general require specific types of fuel. Therefore, the need exists for more efficient and/or more adaptable turbine technologies for propelling vehicles and producing energy and/or electricity.
FIG. 1B shows a conventional rocket engine 130, including fins 132, a nose cone 135, a payload or payload system 140, and guidance system 145, a fuel tank 150, an oxidizer tank 160, pumps 165 feeding fuel and oxidizer from the fuel tank 150 and oxidizer tank 160, respectively, and a combustion chamber 170 with a nozzle 175. Combustion of the fuel using the oxidizer in the combustion chamber 170 creates thrust for moving the payload (e.g., in the payload system/storage area 140) a long distance. However, fuel and oxidizer must be stored in the rocket housing, and the weight of the fuel and oxidizer necessitates more fuel and oxidizer (e.g., to move the fuel and oxidizer), and decreases the efficiency of the engine.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.